Tolling motor, can you get too big

[njdrt-rdr]

I have a 12 foot rowboat that was left at my house I'm fixing up for my son and myself to go finish. Pretty well done, just waiting on Spring.
I am going to add a electric trolling motor. Was originally going to go with something like 30lb, but then I got a gift card for my birthday and I have a couple extra bucks. So I began thinking that if we liked fishing from this boat, I might wind up getting something bigger and could port the trolling motor to that boat. So with prices and rebates going on, I can get a like a 45 or 50 lb motor for not much more than I was originally planning on spending. So my question is can you go too big of a trolling motor on a small boat.

Thanks,
Nick

 

[John_S]

Re: Tolling motor, can you get too big

If you have reserve thrust, you don't have to use it. But, if it is windy or heavier current, its good to have. If you are using for main power, top speed of the 45/50 will be a little more than the 30. Probably less than 1 mph difference.

 

[Silvertip]

Re: Tolling motor, can you get too big

30 - 35# is plenty for that boat unless as was mentioned, you fish in extremely windy conditions or where there are fast currents. Be aware that a 45 - 50# motor will pitch you out of the boat if you hit high speed while someone is standing.

 

[njdrt-rdr]

Re: Tolling motor, can you get too big

Yes, this will be my main power.
I assumed going full throttle from a stop would not be a good idea.
Can't tell you about wind, but a couple of the reserviors I plan on fishing, I've been told the wind can come up quick and unexpected on them.

 

[Silvertip]

Re: Tolling motor, can you get too big

Have you done the necessary electrical calculations to determine how far or how long you can run that motor on any given size battery. Using a troller for main propulsion is not generally a good idea unless you are on very small water. Look at it this way:
1) a 30# motor draws about 30 amps at its fastest setting. A 50/55# draws about 50 amps.
2) Because you run a 1/2 speed does not mean the motor draws 1/2 the current. That calculation is hard to make because the size of the boat, wind, etc affect that number dramatically.
3) Most deep cycle batteries have a RESERVE MNUTES rating on the label stated as xxx min @ 23A (some at 25A). What that means is the battery can deliver 23 amps (or 25 amps) for xxx minutes before it can no longer deliver that amperage.
4) Armed with this info, lets assume you run the motor for two hours at full speed (or four hours at 1/2 speed) which would consume very close to the same amperage. For a 30# motor you would have drawn 60 amps from the battery in those 2 or 4 hours.
5) Since reserve minutes were stated at 23 amps (or 25 amps) you are drawing a little over the batteries rating (30 vs 23) each hour. A 50/55# motor would be drawing double the batteries rating 50 vs 23).
6) A group size 27 deep cycle battery has a typical reserve capacity of 175 - 185 minutes (a little under 3 hours to a little over 3 hours.) So that would be about the maximum run time for a 30# motor. The larger motor would cut that run time by close to half.

The long and short of this is that if you are caught on the water by a sudden storm and you've been trolling for a good amount of time, you may not have enough battery to get you out of harms way. A dual battery setup would be highly recommended but if you push your luck you could still be caught short of juice.

 

[njdrt-rdr]

Re: Tolling motor, can you get too big

I haven't done the electrical calculations. Nowhere in the motor specs could I find how much power the motor draws, so I didn't think about it. I looked at the battery and the specs are 175 minutes at 23 amps

 

[Silvertip]

Re: Tolling motor, can you get too big

I can give you numbers for Minnkota but I need a model and thrust to do that.

 

[fishrdan]

Re: Tolling motor, can you get too big

I have a 12 foot rowboat that was left at my house I'm fixing up for my son and myself to go finish.

Are you the registered/titled owner of this boat? Out here, any powered boat needs to be registered, any non-powered boat does not need to be registered. This could be different in your location.

Tell us more how you are going to use the trolling motor, "trolling", moving from spot-spot and anchoring, positioning? If I was getting a trolling motor as sole means of propulsion (besides the oars) I would get a digital model. The digital TM will cost 2x as much, but at the lower speed settings they will go 2-3 times longer than cheap (speed coil) trolling motors. At full power the digital TM will draw the same amount of power as the cheap speed coil TM though.

 

[njdrt-rdr]

Re: Tolling motor, can you get too big

Sorry, been gone for awhile.
Yes, the boat is registered in my name. It has a gas motor that's been sealed in plastic and put away many years ago (by my brother in law), but most of the lakes I am going to go to are electric only, so I'm not even unwrapping the gas engine. I won't be trolling with the boat, just using it to get from spot to spot to fish.
I wound up with a minkota endura 44lb motor. I good too good of a deal on a used one to pass it up.
Also the lakes I'm going to are so small I could row across them now. I paddle across all of them in my kayak, just looking for more room for fishing with my son in the rowboat.

 

[njdrt-rdr]

Re: Tolling motor, can you get too big

Also another update, I need to buy a new deep cycle battery for the camper so I'll be running a group 29 battery and use it in the boat too. It has 200 reserve minutes, so I think I should have plenty of battery power for the boat.
THanks,
NIck

 

[eclark53520]

Re: Tolling motor, can you get too big

Just for kicks we put a 101lb thrust minn kota bow mount 36v trolling motor on my buddies 12' alumacraft.

She'd run pretty good! Spin around in circles really quick too! lol